Spindles of the known Bulked Continuous Filament (“BCF”) twisting machine adopt the spindle belt transmission mode, which means that a main motor in a machine head box drives a spindle transmission shaft, and the spindle transmission shaft drives spindles to rotate through a spindle belt. The spindle speed is changed through changing of belt pulleys. The spindle belt transmission mode is disadvantaged in complicated operation of change of the spindle speed, large workload, large difference in spindle speed between different spindles, and difficulties in cleaning of space below the spindles caused by occupation. For example, CN1473077A discloses a two-in-one spindle. For another example, CN102212903 A discloses a two-in-one spindle or a twisting spindle. For the spindle-belt transmission mode, the revolving speed of the spindle rod is usually 3,000-6,000 rpm, and the twisting efficiency is relatively low.
The known BCF twisting machine adopts an overfeeding mode that a yarn clamping disc pulls up twisted yarns and conveys the yarns to reeling rollers. A motor in a machine head box respectively drives an overfeeding shaft and a reeling shaft by changing the gear transmission ratio and adjusting the ratio of the revolving speed of the overfeeding shaft over the revolving speed of the reeling shaft. Another method for changing the overfeeding ratio is to change the wrap angle of the yarns on the yarn clamping disc. Changing the overfeeding ratio of the overfeeding structure through the yarn clamping disc must be carried in the halt mode, and the method of changing the gear transmission ratio and the method of changing the wrap angle of the yarns on the yarn clamping disc are both relatively complicated, massively labored and time-consuming.
The existing tension adjusters are usually complicated in structure. Common tension adjusters include hysteresis tensioner and electromagnetic tensioner. For example, Cao Xia stated that changing excitation could generate a relatively large effect on the torque in the Electromagnetic Yarn Tensioner Principle and Dynamic Property Testing and Analysis. However, affected by the number of the magnetic poles, the torque is fluctuating on the circumference. Such fluctuation has bigger effects when the revolving speed is lower.